Chris Kaposy wonders about the impact of mRNA vaccines that treat cancer on the anti-vaccine movement.

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Recent advances in mRNA vaccine technology hold the promise that vaccines could become part of an effective treatment for various forms of cancer. After a successful phase 2 trial, mRNA vaccines are now being used in a phase 3 trial for the treatment of melanoma. In the UK, the National Health Service has set up a program called the “Cancer Vaccine Launch Pad”, which is a platform for recruiting cancer patients into clinical trials in this cutting-edge area of research.

The vaccines are designed to target neoantigens generated by tumours, and then engage the patient’s immune system to ramp up an individualized anti-tumour response to the cancer. Patients have tumour tissue removed via surgery, and the tissue is genetically sequenced. Artificial intelligence can be used to develop a profile for targeting dozens of these neoantigens, so that the resulting mRNA vaccine is individualized to the patient.

Photo Credit: Wikimedia Commons. Image description: A vial of mRNA COVID-19 vaccine.

The phase 2 melanoma study involved 157 people with stage 3 or 4 skin cancer. After surgery to remove the tumour, the vaccine lowered the risk of a recurrence of cancer or death by 49% and lowered the risk of their cancer spreading by 62%, as compared to the control group who received only the current standard of care. These results have made some clinicians optimistic that similar immunotherapy strategies using vaccines could be successful in treating cancer in other parts of the body. The Cancer Vaccine Launch Pad has been created to pursue this hypothesis.

During the COVID-19 pandemic, mRNA vaccines were instrumental in preventing millions of deaths. However, in spite of their success, many people who could have benefited instead resisted vaccination. Some researchers have calculated that in the US, over 230,000 people died because they did not get vaccinated against COVID-19. One of the main drivers of this massive preventable mortality was the anti-vaccination movement, which spread doubts and conspiracy theories about the safety and efficacy of COVID-19 vaccines. Many people refused vaccination because of false, often ridiculous, beliefs about mRNA technology.

Imagine a possible future in which mRNA vaccines become part of the standard of care in the successful treatment of various cancers. Would the use of vaccines to treat cancer diminish the influence of the anti-vaccination movement? Would a vaccine skeptic really refuse a vaccine that would cure their cancer?

Maybe some would refuse. After all, millions of people refused safe and effective vaccines during the pandemic even when people around them were dying from COVID-19. We should not discount the tenacity of belief or the ability to rationalize away empirical evidence. We are all affected by cognitive biases, such as motivated reasoning, to one degree or another. This bias involves skepticism about information inconsistent with our beliefs while being open to information that confirms what we believe. Though we all prone to flaws in our reasoning, we are also able to break out of this irrational cycle.

I venture that if mRNA vaccines continue to show promise in the treatment of cancer, many will turn away from anti-vaccination messaging. In the US, COVID-19 vaccine uptake amongst high-risk groups such as elderly people was high, even in areas where uptake was below average for the rest of the population. For example, in Iowa 95% of people 65 and over were vaccinated (higher than the national average), whereas only 68% of people 18 to 64 were vaccinated, which was below the national average. One explanation for this dynamic is that decisions about vaccination might involve balancing between the perceived risk of the vaccine against the real risk of not getting vaccinated. If the risk of illness is high, as it was for elderly people during the pandemic, vaccine skepticism becomes itself a risky proposition. So if you are facing a melanoma diagnosis, and a vaccine offers the possibility of a cure, the balance of risks weighs heavily in favor of vaccination.

Many have lamented the paradox of vaccines, when used for disease-prevention, being victims of their own success. When we are healthy, we may not see ourselves as at risk, and thus discount the need for vaccination while overestimating the risks of vaccination. Vaccines used as treatment do not encounter this difficulty because illness has already happened.

If we are to predict how these new mRNA vaccines will affect anti-vaccine attitudes, there is still an opening for vaccine skeptics to make a distinction between treatment and prevention. Though vaccine opponents might support vaccines as treatment, they might remain skeptical about preventive uses.

However, this distinction highlights a profound ethical failure of the anti-vaccination movement. The use of vaccines for prevention has a built-in ethical purpose. Vaccination is a step I can take in order to help preserve the health of others. It is a sympathetic and other-regarding health intervention. If we agree to be vaccinated only when it is necessary for our own health, like for cancer treatment, we lose sight of this ethical aspect of vaccination.

A further insight we can draw: even though it may be hard to avoid cognitive biases in our decision-making, there comes a point when the demands of reality break through. When our lives are threatened, maybe vaccine misinformation loses its grip.

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Chris Kaposy is an Associate Professor at the Memorial University Centre for Bioethics, and an editor of the Impact Ethics blog. He is author of The Beautiful Unwanted: Down Syndrome in Myth, Memoir, and Bioethics.